Numerous processes are known for the coating of textile substrates, e.g. non-woven fabrics, fabrics and gauze materials. Most of the coating compounds are adhesive compounds, which are applied for the firm joining of a substrate to the coated substrate in the adhesive state or are made adhesive after application, the adhesive compound being brought into a stable state after adhesion has taken place. High demands are made on such joints in the textile industry with respect to the binding strength, the durability, lack of sensitivity to external influences and elasticity and these are fulfilled to a varying extent by the known processes, as will be shown hereinafter.
The known foil coating in which a separately produced foil of thermoplastic material is pressed onto a preheated textile substrate or an extruded foil is applied in the still warm state to the substrate and is pressed onto the latter, as well as surface coating in which a thermoplastic powder mixed to form a paste is scraped onto a textile web, dried, heated and adhered to the substrate in the slightly liquid state by roller pressure are only used to a limited extent in the textile field, because continuous, uninterrupted thermoplastic coatings during the subsequent adhesion to other textile substrates through temperature, time and pressure have excessive thermal and washing shrinkage values particularly for the clothing industry and also give the end product a non-textile feel.
In the known sprinkling or dusting process, a thermoplastic coating material preground or screened out to a particular particle size distribution is sprinkled onto a preheated textile web, further heated in an oven and then firmly adhered to the textile substrate in the slightly liquid state by roller pressure. As such coatings are irregular, substrates coated in this way after adhering to other thin, smooth upper-materials conventionally used especially in the shirt and blouse industry lead to an orange skin-like surface of the article of clothing following a cleaning treatment.
In the net coating process, an extruded net or a longitudinally slotted foil is spread out and adhered to the preheated textile web. When the stretched net is heated, the connection points tear and the now projecting extensions draw back again into the intersections of the net, so that a non-continuous, punctiform coating of excellent regularity is obtained, but this process is little used because it is uneconomic.
The regular partial, e.g. punctiform coating of the substrate with an adhesive material represents an essential requirement of the clothing industry, obviously whilst respecting the aforementioned requirements. Various processes are known for this. Rotary screen process printing is very widely used in which thermoplastic powder mixed to form a paste by means of binders is applied by a doctor blade with the desired opening pattern to the substrate through the openings of a cylinder screen printing block moving along the substrate. After drying the binder, the thermoplastic material is partly melted and joined to the substrate by roller pressure. This process is also known in conjunction with the use of a ground thermoplastic adhesive material, but the same uniformity as obtained in the processing of pastes is not achieved. The end product is in fact similar to that obtained with the sprinkling or dusting process and has the same disadvantages.
The known intaglio printing-based processes are very economic. Such processes have proved advantageous in connection with the use of a thermoplastic powder, which is scraped onto a roller having depressions arranged in the desired way. A preheated textile web receives the powder, which is further heated in a continuous heating furnace and then firmly adhere to the substrate by roller pressure.
All the known processes function with thermoplastic materials ground and/or screened to particular particle sizes, which is expensive.